An apparatus for producing films or layers on substrates or wafers by conveyorized atmospheric pressure chemical vapor deposition (APCVD) is described in U.S. Pat. No. 4,834,020 and owned by assignee. This patent is expressly incorporated herein by reference.
In general, the APCVD apparatus includes a conveyor belt which transports a wafer or substrate through one or more coating chambers. Each coating chamber includes an injector for creating and maintaining a chemical vapor atmosphere at the wafer or substrate surface such that a reaction occurs between the chemical vapors or between the chemical vapors and the wafer or substrate. The reaction byproducts form a layer on the wafer or substrate to produce a layer or film.
An important element in creating and maintaining the chemical vapor atmosphere at the wafer surface is the injector. The injector receives a number of gases and discretely conveys them to the area above the surface of the wafer or substrate where they mix, react and then form a layer on the wafer or substrate.
The gases must be uniformly mixed over the surface of the wafer or substrate in order to provide a proper chemical reaction. When the gases are not uniformly delivered, they do not mix properly. Thus, the chemical reaction that transpires is one with undesirable chemical concentrations. Consequently, defective films or coatings are deposited on the wafers or substrates. Therefore, to insure a proper film or coating, the gases must be introduced substantially uniformly.
To achieve an advance in the art of depositing a film or coating on a wafer or substrate it is important to refine the apparatus and method of delivering gaseous chemicals to a wafer or substrate. This largely involves refining the means for achieving a uniform, or laminar, flow of reaction chemicals. The prior art has met with limited success in achieving such a uniform flow of reaction chemicals.